Paediatrics




Sidra researcher studies new percutaneous valve for young cardiac patients

Middle East Health speaks to Professor Ziyad M Hijazi, MD, MPH, FACC, MSCAI, the Acting Chief Medical Officer, Service Chief – Pediatrics and Director at Sidra’s Cardiovascular Center of Excellence in Doha and to James A. Hunter, MD, Professor of Pediatrics and Internal Medicine at Rush University Medical Center, Chicago, about new percutaneous valves for paediatric patients that they are researching.


Middle East Health: Can you give me some background about percutaneous valves?

Ziyad M Hijazi & James A. Hunter: Percutaneous valves mean valves that can be implanted in the body without open heart surgery, via a catheter from the groin most of the time. They were implanted for the first time in September 2000 in a child in Paris. Valves are designed for both children and adults. Unfortunately, because of the size of the catheter required, small children are not eligible for them yet; we are working on miniaturization of technology. The current valves are made of either cow tissue or pig tissue. Currently, we are also working on stem cells … so it will be the patient’s own tissue. The first human valve was developed and implanted in a child in Paris. In 2002, the first valve implanted in the aortic position was also in France.

Middle East Health: Can you give some journal references to the research?

Ziyad M Hijazi & James A. Hunter: Here are some references: A. Bonhoeffer P, Boudjemline Y, Saliba Z, et al. Percutaneous replacement of pulmonary valve in a rightventricle to pulmonary-artery prosthetic conduit with valve dysfunction. Lancet 2000;356:1403–1405. B. Garay F, Webb J, Hijazi ZM. Percutaneous replacement of pulmonary valve using the Edwards-Cribier percutaneous heart valve: first report in a human patient. Catheter Cardiovasc Interv 2006;67:659–662. C. Kenny D, Hijazi ZM, Kar S, et al: Percutaneous implantation of the Edwards SAPIEN transcatheter heart valve for conduit failure in the pulmonary position. J Am Coll Cardiol 2011;58:2248-56. D. McElhinney DB, Hellenbrand WE, Zahn EM. Short- and medium-term outcomes after transcatheter pulmonary valve placement in the expanded multicenter US Melody Valve trial. Circulation 2010;122:507-516.

Middle East Health: What is unique about these valves?

Ziyad M Hijazi & James A. Hunter: The valve I’m working on (the Venus P valve) has special features: first, it can be implanted in patients who have what we call “trans-annular patch” and those patients represent the majority of patients after tetralogy of Fallot repair. The currently available valves can be implanted only in patients who received a “conduit” between the right ventricle and the pulmonary artery and these patients represent only 15% of the patients. Second, these valves can be inserted in the body using a smaller catheter making the number of children eligible larger.

Middle East Health: I am told that you want to use them in paediatric patients to reduce Interview the number of open heart surgery cases. What medical conditions will this cover? What age group?

Ziyad M Hijazi & James A. Hunter: Yes, my goal is reduce the number of open heart surgeries a child needs in his/her lifetime … usually children (who require heart valve replacement) will require about four open heart surgeries in their lifetime … because the valves do not last long (10-15 years), some valves even do not last 2-5 years. So, if I put this valve without open heart surgery, I succeed in reducing the number of operations these kids endure in their life. We use these valves for a variety of conditions. Most commonly, patients after tetralogy of Fallot repair. This disease is common in children with congenital heart disease. Almost all tetralogy of Fallot patients will require a valve at one point … the valve can be put surgically via open heart surgery or via a catheter… that is where my valve comes in handy. Other conditions include patients who undergo what we call a Ross operation and of course any patient who receives a surgical valve between the right ventricle and pulmonary artery. The age group iscurrently anyone older than 5 years old. But quite honestly, it is not the age factor, it is the weight. We can put this valve in any patient with a weight of more than 20 kg.

Middle East Health: I understand they are not being used in Europe or the US. Is this an issue for you? In other words – that they have not been used extensively enough to prove their efficacy?

Ziyad M Hijazi & James A. Hunter: True, this valve is relatively new, about one year. They are still investigational and not yet approved for commercial use. I did “FIM” (first in man) last year in China with excellent results. We have done extensive animal work that showed great results. So, the fact that it is not yet approved in the US and Europe does not mean it is not good, simply we are new and we believe these valves will be approved at one point. That is why we are doing an extensive study and collecting a lot of information so that we can submit to the FDA and European notified body for commercial approval.

Middle East Health: How many cases do you see per year? And how many cases do you envisage these valves will assist?

Ziyad M Hijazi & James A. Hunter: In Qatar we expect about 20 cases per year. However, if we are in the US, we expect much larger population, around 5,000 per year. Not all of them we can do it without open heart surgery. Worldwide we expect 100,000 cases per year.

Middle East Health: Can you explain the procedure to insert the valves?

Ziyad M Hijazi & James A. Hunter: The procedure is done under general anaesthesia. We insert a catheter from the femoral vein in the groin and under X-ray guidance, we deploy the valve (the valve is mounted over a catheter), once in the desired position, we retract the catheter and the valve made of a stent, will deploy and start functioning immediately. The procedure for the most part is very safe, the patient goes home within 24 hours and they can go back to activities within a week.

Middle East Health: What challenges do you envisage with inserting these valves?

Ziyad M Hijazi & James A. Hunter: The most important challenge is the sizing of the valve. Each patient has different size and choosing the correct size is crucial so that the valve does not migrate at all.

Date of upload: 16th May 2014

                                  
                                               Copyright © 2014 MiddleEastHealthMag.com. All Rights Reserved.